int *getConcatenation(int *nums, int numsSize, int *returnSize)
{
    int *ret = (int *)malloc(sizeof(int) * numsSize * 2);
    int i;
    for (i = 0; i < numsSize; ++i)
    {
        ret[i] = ret[i + numsSize] = nums[i];
    }
    *returnSize = 2 * numsSize;
    return ret;
}